Electrical systems often comprise multiple sources of signals which are transferred in signal paths from such sources to loads for those signals, and which signals require similar signal processing in those paths in selectably different amounts before such signals are transferred to their loads. Assuming that there is a fixed total signal processing capacity available to fulfill that requirement, one way to satisfy it is to divide the total capacity into a plurality of similar circuit sections which are greater in number than said paths and all perform the same signal processing function, and to then selectively allocate different numbers of said circuit sections to different ones of said paths as required. That selective allocation often requires, however, the making of a great number of electrical connections, the undertaking of which can be laborious and expensive in the absence of any means to facilitate it.